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sd_bus_slot_set_destroy_callback(3) — Linux manual page

SD_BUS_...ALLBACK(3) sd_bus_slot_set_destroy_callbackSD_BUS_...ALLBACK(3)

NAME        top

       sd_bus_slot_set_destroy_callback,       sd_bus_slot_get_destroy_callback,       sd_bus_track_set_destroy_callback,       sd_bus_track_get_destroy_callback, sd_bus_destroy_t - Define the       callback function for resource cleanup

SYNOPSIS        top

#include <systemd/sd-bus.h>typedef int (*sd_bus_destroy_t)(void *userdata);int sd_bus_slot_set_destroy_callback(sd_bus_slot *slot,sd_bus_destroy_tcallback);int sd_bus_slot_get_destroy_callback(sd_bus_slot *slot,sd_bus_destroy_t *callback);int sd_bus_track_set_destroy_callback(sd_bus_track *track,sd_bus_destroy_tcallback);int sd_bus_track_get_destroy_callback(sd_bus_track *track,sd_bus_destroy_t *callback);

DESCRIPTION        top

sd_bus_slot_set_destroy_callback()setscallback as the callback       function to be called right before the bus slot objectslot is       deallocated. Theuserdata pointer from the slot object will be       passed as theuserdata parameter. This pointer can be set by an       argument to the constructor functions, seesd_bus_add_match(3), or       directly, seesd_bus_slot_set_userdata(3). This callback function       is called even ifuserdata isNULL. Note that this callback is       invoked at a time where the bus slot object itself is already       invalidated, and executing operations or taking new references to       the bus slot object is not permissible.sd_bus_slot_get_destroy_callback()returns the current callback       forslot in thecallback parameter.sd_bus_track_set_destroy_callback()andsd_bus_track_get_destroy_callback()provide equivalent       functionality for theuserdata pointer associated with bus peer       tracking objects. For details about bus peer tracking objects, seesd_bus_track_new(3).

RETURN VALUE        top

       On success,sd_bus_slot_set_destroy_callback()andsd_bus_track_set_destroy_callback()return 0 or a positive       integer. On failure, they return a negative errno-style error       code.sd_bus_slot_get_destroy_callback()andsd_bus_track_get_destroy_callback()return positive if the destroy       callback function is set, 0 if not. On failure, they return a       negative errno-style error code.Errors       Returned errors may indicate the following problems:-EINVAL           Theslot ortrack parameter isNULL.

NOTES        top

       Functions described here are available as a shared library, which       can be compiled against and linked to with thelibsystemd pkg-config(1) file.       The code described here usesgetenv(3), which is declared to be       not multi-thread-safe. This means that the code calling the       functions described here must not callsetenv(3) from a parallel       thread. It is recommended to only do calls tosetenv()from an       early phase of the program when no other threads have been       started.

HISTORY        top

sd_bus_destroy_t(),sd_bus_slot_set_destroy_callback(),sd_bus_slot_get_destroy_callback(),sd_bus_track_set_destroy_callback(), andsd_bus_track_get_destroy_callback()were added in version 239.

SEE ALSO        top

systemd(1),sd-bus(3),sd_bus_slot_set_floating(3),sd_bus_add_match(3),sd_bus_track_new(3),sd_bus_slot_set_userdata(3),sd_bus_track_set_userdata(3)

COLOPHON        top

       This page is part of thesystemd (systemd system and service       manager) project.  Information about the project can be found at       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a       bug report for this manual page, see       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.       This page was obtained from the project's upstream Git repository       ⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11.  (At that       time, the date of the most recent commit that was found in the       repository was 2025-08-11.)  If you discover any rendering       problems in this HTML version of the page, or you believe there is       a better or more up-to-date source for the page, or you have       corrections or improvements to the information in this COLOPHON       (which isnot part of the original manual page), send a mail to       man-pages@man7.orgsystemd 258~rc2SD_BUS_...ALLBACK(3)

Pages that refer to this page:sd-bus(3), sd_bus_slot_set_floating(3), sd_bus_slot_set_userdata(3), systemd.directives(7), systemd.index(7)

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